perf kvm: Make function only used by 'perf kvm' static

No need to have this polluting util.h, it was polluted enough already.

Link: http://lkml.kernel.org/n/tip-wfdidqlwbvi5y0s61kv6z2gn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index d86ac0a..129af3e 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -36,6 +36,20 @@
 #include <pthread.h>
 #include <math.h>
 
+static const char *get_filename_for_perf_kvm(void)
+{
+	const char *filename;
+
+	if (perf_host && !perf_guest)
+		filename = strdup("perf.data.host");
+	else if (!perf_host && perf_guest)
+		filename = strdup("perf.data.guest");
+	else
+		filename = strdup("perf.data.kvm");
+
+	return filename;
+}
+
 #ifdef HAVE_KVM_STAT_SUPPORT
 #include "util/kvm-stat.h"